1. Field of the Invention
The present invention relates to aqueous two-component coating compositions containing water dispersible compounds, which contain alkoxysilane groups and are substantially free from isocyanate groups, and aqueous polyhydroxy polyesters.
2. Description of the Prior Art
Two-component aqueous compositions containing a water dispersible polyisocyanate component and various water dispersible or water soluble polyhydroxy components are known and described in U.S. Pat. Nos. 5,075,370, 5,389,718, 5,387,642, 5,372,875, 5,336,711, 5,344,873 and 5,459,197. The aqueous compositions may be used for a wide range of commercial applications such as adhesives, sealants or coatings for various substrates including textile fabrics, plastic, wood, glass fibers and metals. Chemical resistance, abrasion resistance, toughness, tensile strength, elasticity and durability are among the many desirable properties of these coatings.
One of the known two-component compositions is based on water dispersible polyisocyanates and aqueous polyhydroxy compounds containing ester and/or carbonate groups. One disadvantage of these systems is that the resulting coatings do not possess adequate hardness for certain applications. In addition, it is advantageous in certain applications to avoid the use of polyisocyanate resins for environmental and industrial hygiene reasons.
Accordingly, it is an object of the present invention to provide two-component aqueous compositions containing new non-isocyanate co-reactants, which can be used to prepare coatings having improved hardness.
This object may be achieved with the aqueous two-component coating compositions according to the present invention, which are based on water dispersible compounds containing urea and alkoxysilane groups and an aqueous polyhydroxy compound containing ester and/or carbonate groups. These compounds containing urea and alkoxysilane groups may be prepared by reacting a polyisocyanate component with compounds containing secondary amino groups and alkoxysilane groups.